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Water Water’s Functions • Carries nutrients and waste products • Actively participates in chemical reactions • Serves as a solvent for minerals, vitamins, amino acids glucose, and other small molecules Water’s Functions • Serves as a lubricant and cushion around joints • Acts as a shock absorber(eyes, spinal column, amniotic sac) • Aids in maintaining body’s temperature Body’s Water Balance • Water makes up about 60 % of the body’s weight • A change in the body’s water can bring a change in the body weight – Sweating: water loss during exercise – Edema: water retention during pregnancy Water Balance • Water loss necessitates water intake – Urine, sweat, exhalation, feces • Dehydration can have serious consequences RECOMMENDATIONS - 2004 • No rule of thumb regarding # of glasses – AI - 91 oz for women, 125 oz for men – Water, juice, milk, coffee, tea, soda, fruits, vegetables and other foods and beverages • Let thirst be your guide – Physical activity – Heat exposure Figure 10.6 The consequence of a difference in osmotic pressure (a) A solute such as NaCl is more concentrated outside the cell than inside. (b) Water flows by osmosis out of the cell until the concentrations are equal. Neurons in certain brain areas detect their own dehydration and trigger thirst. Water Recommendations and Sources • Hard water is high in calcium and magnesium • Soft water is high in sodium – It also dissolves cadmium and lead from pipes • If a person has lead pipes, this can be a problem with long term use Electrolytes • Electrolytes (sodium, potassium, chloride) help keep fluids in the proper compartments – Intracellular water – Extracellular water Electrolytes • Enable nerves to respond • Signal muscles to contract Primary electrolytes-major minerals • More than 0.1 grams (or 100 mg) required per day in the diet • These include: – – – – Chloride Phosphorus Potassium Sodium Sodium: + ion of table salt (NaCl) • No known human diet lacks sodium • Minimum requirement about 500 mg/day – estimated safe and adequate Daily intake • Average intake in US for men = 3300 mg/day(equal to 8 grams of salt/day) Calcium • Roles: – 99% in bones and teeth – 1% • Cell membranes: regulates transport of ions into and out of cells – Nerve to nerve transmission » Nerve to muscle transmission • Helps hold cells together • Blood Clotting • Co-factor for several enzymes Calcium: Blood Levels Highly Regulated: 4 ways • 1. Protein-bound Ca released to become available for use by cells • 2. Increased Calcium absorption from gut through activation of Vitamin D • 3.Increased Calcium released from the bone through parathyroid hormone activation of Vitamin D • 4. Kidneys conserve Calcium Calcium RDA 1000-1200 mg/day for Adults • Foods rich in Calcium: – – – – – 1 cup milk: 1 oz cheese: 1/2 cup spinach: 1 orange 1 cup Yogurt (fat free or low fat) 300 mg 200 mg 106 mg 52 mg 350-400mg Calcium Deficiency • Rickets: in children. Same as Vitamin D deficiency – Bow legs, poor bone formation • Osteomalacia: in adults. Same as Vitamin D deficiency – poor bone formation • Osteoporosis: Multiple causes Calcium and Osteoporosis • • • • • • • Low Calcium intake Poor Vitamin D status female family history small skeleton menopause smoking high animal protein drinking alcohol bed rest white/Asian • Vitamin D improves symptoms of knee osteoarthritis Trace Minerals: Micro minerals • One definition: less than 0.1 gram(100 mg/day) need in the diet – Some trace minerals: • • • • Iron (Fe) Iodine(I) Zinc(Zn) Fluoride(F) Iron • Component of hemoglobin and myoglobin – hemoglobin carries oxygen in blood – myoglobin stores oxygen in muscle cells • Deficiency: – RDA set at 18 mg/day for females and 8 mg/day for males – If iron stores exhausted, iron deficiency anemia • microcytic, hypochromic anemia • reduced Hemoglobin synthesis, RBCs are small and Megaloblastic anemia Iron Absorption • Most iron we eat doesn’t get absorbed – What helps? • vitamin C • MFP factor: some factor in meat, fish and poultry helps absorb iron • need for iron – What hurts absorption? • tea coffee • Calcium and Phosphorus • phytates and fiber and oxalates Factors Affecting Iron Absorption • Increase • Decrease • • • • • • • • • • • • • Gastric Acid Heme iron Demand Low body stores MPF Vitamin C Phytic Acid Oxalic Acid Polyphenols Full body stores Excess of other min. Reduced gastric acid Some antacids Iron: Method of Absorption • Iron in food – Absorbed into cells that line GI tract – If blood levels of iron are low • iron picked up from cells by the blood and carried to places where RBCs are made – If blood levels of iron are ok • iron stays in cells lining the GI tract – In 3 to 5 days the cells are worn out and fall into the lumen of the GI tract and mix with the remains of digestion Iron Overload • 2 Types of Overload – 1. Hereditary Defect: Hemochromatosis • Very efficient absorption • High circulating Fe which is laid down in tissues of liver, heart and causes damage – 2. High Iron ingestion: Hemosiderosis • Even with control of absorption, high intake can result in toxic side effects • We don’t have a good mechanism of getting rid of absorbed iron Iron Sources • • • • • • 4 oz of lean roast = 3 mg 4 oz liver = 7 mg 1/2 cup beans = 4.15 mg 1 cup broccoli = 1.12 mg 1 slice mixed grain bread = 0.8 mg 1 cup raisins = 3.12 mg Zinc • Part of nearly 100 enzymes • Role in immune function • Absorption affected by zinc status, phytates, iron • Hinders absorption of copper and iron • Sources: red meats, eggs, vegetables Zinc Deficiency • • • • • • Growth delay Altered digestive function Impairs immune response Vitamin deficiencies Loss of appetite Slow wound healing Iron and Zinc Deficiency in School-age Children 80 60 %40 20 0 Selenium • Functions – Antioxidant system – Thyroxine and immune function • Deficiency – Keshan disease – Impaired immune response, cognitive function, muscle pain, wasting – The Link between Selenium and Chemoprevention: A Case for Selenoproteins -- Diwadkar-Navsariwala and Diamond 134 (11): 2899 -- Journal of Nutrition Selenium – RDA 55 mg/day • • • • Sources Nuts Seafood Pasta Fluoride • Becomes part of crystalline deposits in bones and teeth – In teeth, resistant to tooth decay (dental caries) – 1 part per million in water supply optimum resistance – Higher than that can result in tooth mottling • Brown coloration on teeth – Much higher (18 ppm) can result in fluoridosis • Bone malformation Copper • Coenzyme – Part of ceruloplasmin • Deficiency • Toxicity